Jeffrey Palermo

Why Migrate to DevDrive?

Windows DevDrive is a specialized volume format that provides dramatic performance improvements for development workloads:

• ~40% faster Git operations
• ~25% faster build times
• ~30% faster file I/O operations
• Optimized for development patterns (many small files)
• Transparent — existing tools work without configuration changes

If you’re managing dozens of source repositories, moving them to a DevDrive can shave significant time off your daily development cycle.

Prerequisites

Before starting, ensure you have:

• Windows 11 or Windows Server 2022 (DevDrive requires recent Windows versions)
• Administrator privileges (required for DevDrive creation and symbolic links)
• At least 150-200 GB free space (depending on your codebase size)
• GitHub Copilot CLI installed (winget install GitHub.Copilot.CLI or download from github.com/copilot)
• PowerShell 7+ (recommended) or Windows PowerShell 5.1+

Check Your Windows Version

# Verify you're on Windows 11 or Server 2022
[System.Environment]::OSVersion.VersionString

# You should see something like:
# Microsoft Windows NT 10.0.26100.0

Step 1: Create a New DevDrive

Option A: Using Windows Settings (GUI)

1. Open Settings → System → Storage
2. Scroll down to find Advanced storage options
3. Click “Disks & volumes” (or “Dev drives” depending on your Windows version)
4. Look for unallocated space on your secondary drive (in this example, the D: drive)
5. Click “Create a Dev drive” button
6. Configure the DevDrive:
   • Location: Select your secondary drive (e.g., D:)
   • Size: At least 150-200 GB for typical development workloads
   • Label: Name it something descriptive like “DevDrive-Projects” or “DevDrive-Repos”
7. Click “Create” and wait 2-5 minutes for initialization

Option B: Using PowerShell (Command Line)

# Requires Administrator privileges
# Run as Administrator!

# Create a 200 GB DevDrive on D: with label "DevDrive-Repos"
New-DevDrive -Drive D: -Size 200GB -Name "DevDrive-Repos"

# Verify creation
Get-Volume | Where-Object { $_.FileSystem -eq "DevFS" }

# You should see your new DevDrive listed

⏱️ Time: 2-5 minutes for DevDrive initialization

Step 2: Open GitHub Copilot CLI

GitHub Copilot CLI automates the entire migration process. Launch it:

copilot

Step 3: Run the Migration Prompt

Copy and paste this prompt into Copilot CLI (adapt the paths and repository count to your setup):

Replace:

• YourUsername with your Windows username
• D:\ with your DevDrive path (if using a different letter)

Press Enter and let Copilot CLI handle the rest.

Copilot CLI Response

The CLI will analyze your request and create a structured plan:

🔍 Analyzing your setup...
📋 Creating implementation plan...

PLAN CREATED:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Problem: Migrate repositories (~85 GB) from C:\Users\YourUsername\source\repos 
to DevDrive (D:\) while maintaining backward compatibility

Approach:
1. Create a symbolic link at C:\Users\YourUsername\source\repos → D:\
2. Move all repositories from C:\Users\YourUsername\source\repos to D:\
3. Verify all paths resolve correctly
4. Test Git operations through the symbolic link

Strategy:
✓ Single directory link (more maintainable than individual links)
✓ Target layout: All repos directly under D:\ (D:\repo-name structure)
✓ Backward compatibility: Old paths continue working transparently

Ready to proceed? (Type 'start' to begin migration)

Step 4: Watch the Automated Migration

Type start to begin:

start

Copilot CLI will execute the migration in phases:

Phase 1: Pre-Migration Validation

=== PHASE 1: PRE-MIGRATION VALIDATION ===

✓ Source directory exists
✓ DevDrive (D:\) exists
✓ Source size: 85.27 GB
✓ D:\ free space: 252.65 GB
✓ Sufficient space available
✓ Path is a regular folder (ready for conversion)
✓ No open handles detected

=== PHASE 1 COMPLETE ===

What it checks:

• Source and target paths exist
• Sufficient free space
• No open file locks
• Permissions are correct

Phase 2: Migration

=== PHASE 2: MIGRATING REPOSITORIES ===

Found N repositories to migrate
Using Robocopy for efficient migration with resume capability...

Moving: project-api
  ✓ Success
Moving: framework-core
  ✓ Success
Moving: webapp-frontend
  ✓ Success
...
Moving: infrastructure-tools
  ✓ Success

=== PHASE 2 SUMMARY ===
Successfully migrated: N
Failed migrations: 0

=== PHASE 2 COMPLETE ===

📊 Migration Details:

• Method: Robocopy (fast, resumable, maintains file attributes)
• Time: 6-8 minutes for 85 GB (varies by drive speed)
• Reliability: Automatic retry on failure

Phase 3: Create Symbolic Link

=== PHASE 3: CREATING SYMBOLIC LINK ===

Creating symbolic link...
  Source: C:\Users\YourUsername\source\repos
  Target: D:\

✓ Symbolic link created successfully
✓ Symbolic link verified!

=== PHASE 3 COMPLETE ===

What happens:

• Removes empty source directory
• Creates Windows directory junction using mklink /J
• Verifies link points to correct target

Phase 4: Verification

=== PHASE 4: VERIFICATION & TESTING ===

1. Testing path redirection...
  Old path: C:\Users\YourUsername\source\repos
  Points to: D:\
  ✓ Verified

2. Listing repositories via old path...
  Found N repositories
  ✓ Path is accessible

3. Listing repositories via new path (D:\)...
  Found N repositories

4. Verifying consistency...
  ✓ Repository counts match

5. Testing file access through old path...
  Sample repo: sample-project
  ✓ Can access files

=== PHASE 4 COMPLETE ===

Phase 5: Tool Compatibility Testing

=== PHASE 5: TESTING TOOL COMPATIBILITY ===

Testing Git Integration...
Found Git repo: sample-project
Testing 'git status' via old path...
  ✓ Git commands work through symbolic link

Testing Absolute Path Access...
  C:\Users\YourUsername\source\repos\sample-project
    ✓ Accessible
  D:\sample-project
    ✓ Accessible

=== PHASE 5 COMPLETE ===

Step 5: Verify Everything Works

That’s it! Copilot CLI handles the entire migration automatically.

To verify everything works, test with your tools:

Test 1: Git Operations

cd C:\Users\YourUsername\source\repos\sample-project
git status

Test 2: Open in IDE

• VSCode: code C:\Users\YourUsername\source\repos\sample-project
• Visual Studio: File → Open → navigate to old path
• Rider: File → Open → select old path

Test 3: Build Operations

cd C:\Users\YourUsername\source\repos\my-dotnet-app
dotnet build

✅ All should work without any configuration changes.

Understanding Symbolic Links

How It Works

Windows symbolic links (directory junctions) create a transparent redirect:

Application Request
        ↓
C:\Users\YourUsername\source\repos
        ↓
[Windows Kernel: This is a junction to D:\]
        ↓
D:\
        ↓
Actual Files & Directories

Why It’s Safe

• Transparent — Applications don’t know about the redirect
• Reliable — Windows handles it at the kernel level
• Performant — Negligible overhead
• Recoverable — Data remains on D:\ unmodified
• Tested — Used extensively in Windows and NTFS

Performance Improvements

Once migrated, you’ll see performance gains in development workflows:

Benchmark: Before vs After

Results vary based on disk hardware and repository size

Troubleshooting

Issue: “Access Denied” on Symbolic Link Creation

Solution: Run PowerShell as Administrator (Right-click → “Run as administrator”)

Issue: “Insufficient Space” Error

Solution: Check DevDrive size and ensure you have free space

$drive = Get-Volume -DriveLetter D
$freeGB = [math]::Round($drive.SizeRemaining / 1GB, 2)
Write-Host "Free space on D:\: $freeGB GB"

Issue: Some Repositories Fail to Migrate

Solution: Close all applications accessing the repositories (IDEs, VSCode, file explorers, Git tools, antivirus) and retry.

Resources

• Windows DevDrive Documentation: microsoft.com/dev-drives
• GitHub Copilot CLI: github.com/copilot
• Windows Symbolic Links: docs.microsoft.com/mklink

Summary: Your Migration Checklist

• Verify Windows 11 or Server 2022 version
• Create new DevDrive (150-200 GB)
• Install GitHub Copilot CLI
• Open Copilot CLI: copilot
• Paste migration prompt (customize for your paths)
• Review generated plan
• Type start to execute
• Wait for migration to complete (6-8 minutes)
• Test with Git: git status
• Test with IDE: Open project in VSCode/Visual Studio
• Done! Enjoy 25-40% performance improvements

Rollback (If Needed)

If you need to reverse the migration:

# 1. Remove the symbolic link
rmdir "C:\Users\YourUsername\source\repos"

# 2. Move repositories back from D:\ (all data remains intact)